Project: a 1.5 volt battery eliminator for my garage wall clock.
Background: I love the old clock, but I hate replacing the AA cell in it, so I want to connect it to the mains via a power pack.
I have a DC power pack that provides these nominal DC voltages (at 150 mA) via a slide switch: 1.5, 3, 4.5, 6, 9, 12.
The open circuit DC voltages I measured are: 3.02, 4.87, 6.71, 8.54, 12.63, 16.82 respectively.
When I connect the power pack to the clock in lieu of the battery, using the 1.5 volt switch position, the clock's second hand runs at about twice the correct speed. I'm supposing that the impedance of the clock mechanism is too high to drag the power pack's output down to 1.5 volts, thus I'm putting 3.02 volts onto the clock.
So, I'm seeking suggestions as to how to cheaply regulate the power pack's output voltage to 1.5. I'm pretty rusty on electronics -- I left tech school in 1970 -- but I recall enough to know that my options include: a zener diode circuit or a resistive voltage divider.
I don't know if there's such a thing as a 1.5 volt zener (I think the lowest is 3.3 volts), and I need help with the current/power/resistance calculations for a simple voltage divider.
Any assistance greatly received. Thanks!
Background: I love the old clock, but I hate replacing the AA cell in it, so I want to connect it to the mains via a power pack.
I have a DC power pack that provides these nominal DC voltages (at 150 mA) via a slide switch: 1.5, 3, 4.5, 6, 9, 12.
The open circuit DC voltages I measured are: 3.02, 4.87, 6.71, 8.54, 12.63, 16.82 respectively.
When I connect the power pack to the clock in lieu of the battery, using the 1.5 volt switch position, the clock's second hand runs at about twice the correct speed. I'm supposing that the impedance of the clock mechanism is too high to drag the power pack's output down to 1.5 volts, thus I'm putting 3.02 volts onto the clock.
So, I'm seeking suggestions as to how to cheaply regulate the power pack's output voltage to 1.5. I'm pretty rusty on electronics -- I left tech school in 1970 -- but I recall enough to know that my options include: a zener diode circuit or a resistive voltage divider.
I don't know if there's such a thing as a 1.5 volt zener (I think the lowest is 3.3 volts), and I need help with the current/power/resistance calculations for a simple voltage divider.
Any assistance greatly received. Thanks!